SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9408508d29a156a7f4c4d9648c640c86b2530dde184c300959dafce0d356ccbd' 
  AND token = 'mUusit5D9awTW+u9hKw3ZY5GPVfyByjCUwtIQQ+iVNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}